GNSS Low Power Mode

Application Note

GNSS Module Series

Rev. GNSS_Low_Power_Mode_Application_Note_V2.0

Date: 2016-05-16

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About the Document

History

Revision Date Author Description

1.0 2015-08-21 Connie ZHOU Initial

2.0 2016-05-16 Ziv LIAO

1. Changed the document name from

Fitness_Low_Power_Application_Note to

GNSS_Low_Power_Mode_Application_Note

2. Added GLP mode

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Contents

About the Document ................................................................................................................................... 2

Contents ....................................................................................................................................................... 3

1 Introduction .......................................................................................................................................... 5

2 Power Consumption ............................................................................................................................ 6

3 Quectel NMEA Packet Protocol .......................................................................................................... 7

3.1 Quectel NMEA Packet Format ......................................................................................................... 7

3.2 Packet Type: PQBAUD Set NMEA Port Baudrate ........................................................................ 7

3.3 Packet Type: PQFLP Set the Module into FLP Mode ................................................................... 8

3.4 Packet Type: PQGLP Set the Module into GLP Mode ................................................................. 9

4 Enter into or Exit from Low Power Mode ........................................................................................ 11

4.1 Enter into/Exit from FLP Mode ....................................................................................................... 11

4.2 Enter into/Exit from GLP Mode ...................................................................................................... 11

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Table Index

TABLE 1: AVERAGE CURRENT IN FLP MODE AND NORMAL MODE (L70 MODULE) .......................... 6

TABLE 2: AVERAGE CURRENT IN GLP MODE AND NORMAL MODE (L76 MODULE) .......................... 6

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1 Introduction

Low power mode is an optimized solution for wearable fitness and tracking devices. It provides fitness low

power (FLP) mode for Quectel GPS only modules and GNSS low power (GLP) mode for Quectel

multi-GNSS modules to reduce power consumption with tiny accuracy trading-off. The low power mode

can be easily set by using a specific message.

In low power mode, the module has good route consistence in walking and running scenarios, and can

switch dynamic duty operation automatically. It will come back to normal mode in difficult environment to

keep good accuracy as well, thus realizing maximum performance with the lowest power consumption.

This document is applicable to Quectel GNSS modules.

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2 Power Consumption

The average current in FLP/GLP mode is down to 5mA/7.3mA in static receiving, which is about 40% of

normal mode. The power consumption may increase a little bit in dynamic scenario. The average current

in different open sky scenarios in FLP/GLP mode and normal mode is shown in the table below.

Table 1: Average Current in FLP Mode and Normal Mode (L70 Module)

Scenario In FLP Mode (mA) In Normal Mode (mA)

Static 5.0 12

Walking 5.4 12

Running 5.5 12

Driving 8.5 12

Table 2: Average Current in GLP Mode and Normal Mode (L76 Module)

Scenario In GLP Mode (mA) In Normal Mode (mA)

Static 7.3 18

Walking 9.2 18

Running 9.4 18

Driving 17.6 18

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3 Quectel NMEA Packet Protocol

This chapter introduces the Quectel NMEA packet protocol which is a set of extension messages of the

standard NMEA packet protocol. These messages are used to control the module to enable or disable

FLP/GLP mode. The following table shows the structure of a Quectel NMEA packet.

3.1 Quectel NMEA Packet Format

Preamble TalkerID PktType DataField * CHK1 CHK2 CR LF

*The maximum length of each packet is restricted to 255 bytes.

Packet Contents:

Preamble: One byte character: ‘$’

TalkerID: Two bytes character string: “PQ“

PktType: 1-10 bytes character string. An identifier used to tell the decoder how to decode the packet.

DataField: The DataFileld has variable lengths depending on the packet type. A command symbol ‘,’

must be inserted ahead of each data field to help the decoder to process the DataField.

* : 1 byte character. The star symbol is used to mark the end of DataField.

CHK1,CHK2: Two bytes character string. CHK1 and CHK2 are the checksum of the data between

Preamble and ‘*’.

<CR><LF>: Each NMEA message ends with ‘CR’ and ‘LF’.

3.2 Packet Type: PQBAUD Set NMEA Port Baudrate

PQBAUD Set NMEA Port Baudrate

Write Command

$PQBAUD,W,<baudrate>*Checksu

m<CR><LF>

Response

$PQBAUD,W,OK*Checksum<CR><LF>

If error:

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Parameter

<baudrate> NMEA port baudrate

Could be set to 4800, 9600,14400,19200, 38400, 57600, 115200

Example

$PQBAUD,W,115200*43 //Set NMEA port baudrate as 115200

$PQBAUD,W,OK*40 //Set successfully

1. The command will be effective immediately after setting.

2. Parameter is automatically saved.

3.3 Packet Type: PQFLP Set the Module into FLP Mode

Parameter

<mode> Module operation mode

0 Normal mode

1 FLP mode

<save> Save operation

0 Parameter is not saved, ineffective after restart

$PQBAUD,W,ERROR*Checksum<CR><LF>

Reference

PQFLP Set the Module into FLP Mode

Write Command

$PQFLP,W,<mode>,<save>*Checksu

m<CR><LF>

Response

$PQFLP,W,OK*Checksum<CR><LF>

If error:

$PQFLP,W,ERROR*Checksum<CR><LF>

Read Command

$PQFLP,R, *Checksum<CR><LF>

Response

$PQFLP,R,<mode>*Checksum<CR><LF>

Reference

NOTES

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1 Parameter is saved in flash, effective after restart

Example

$PQFLP,W,1,1*20 //Switch to FLP mode

$PQFLP,W,OK*08 //Set successfully

$PQFLP,R*25 //Query the working mode

$PQFLP,R,1*38 //The module is in FLP mode

The command will be effective immediately after setting.

3.4 Packet Type: PQGLP Set the Module into GLP Mode

Parameter

<mode> Module operation mode

0 Normal mode

1 GLP mode

<save> Save operation

0 Parameter is not saved, ineffective after restart

1 Parameter is saved in flash, effective after restart

Example

$PQGLP,W,1,1*21 // Switch to GLP mode

$PQGLP,W,OK*09 // Set successfully

PQGLP Set the Module into GLP Mode

Write Command

$PQGLP,W,<mode>,<save>*ChkSum

<CR><LF>

Response

$PQGLP,W,OK*ChkSum<CR><LF>

If error:

$PQGLP,W,ERROR*ChkSum<CR><LF>

Read Command

$PQGLP,R*ChkSum<CR><LF>

Response

$PQGLP,R,<mode>*ChkSum<CR><LF>

Reference

NOTE

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$PQGLP,R*24 // Query the working mode

$PQGLP,R,1*39 // The module is in GLP mode

The command will be effective immediately after setting.

NOTE

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4 Enter into or Exit from Low Power

Mode

4.1 Enter into/Exit from FLP Mode

You can follow the steps below to enter into or exit from the FLP mode:

1. Download the firmware that supports FLP mode to the module.

2. Set NMEA port baudrate to 115200. Command $PQBAUD,W,115200*43 can be used to set the baud

rate into 115200. When the module responds $PQBAUD,W,OK*40, the command is executed

successfully.

3. Set the module into FLP mode. Command $PQFLP,W,1,1*20 is used to set the module into FLP

mode. When the module responds $PQFLP,W,OK*08, the command is executed successfully.

4. Wait for at least 5 minutes to allow the module to completely enter into FLP mode.

5. Make the module exit from FLP mode. Command $PQFLP,W,0,1*21 is used to make the module exit

from FLP mode. When $PQFLP,W,OK*08 is returned, it means the module has exited from FLP

mode successfully.

4.2 Enter into/Exit from GLP Mode

You can follow the steps below to enter into or exit from the GLP mode:

1. Download the firmware that supports GLP mode to the module.

2. Set NMEA port baudrate to 115200. Command $PQBAUD,W,115200*43 can be used to set the baud

rate into 115200. When the module responds $PQBAUD,W,OK*40, the command is executed

successfully.

3. Set the module into GLP mode. Command $PQGLP,W,1,1*21 is used to set the module into GLP

mode. When the module responds $PQGLP,W,OK*09, the command is executed successfully.

4. Wait for at least 5 minutes to allow the module to completely enter into GLP mode;

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5. Make the module exit from GLP mode. Command $PQGLP,W,0,0*21 is used to make the module

exit from GLP mode. When $PQGLP,W,OK*09 is returned, it means the module has exited from GLP

mode successfully.

1. It is recommended that some necessary commands are set before the module enters into low power

mode. If you need to send commands, please exit from low power mode first.

2. When the module enters into low power mode, 1PPS function will not be supported.

3. When the GPS olny module enters into FLP mode, EASY function will be disabled. You can send

command to enable EASY function after the module exits from the FLP mode.

4. When the low power mode is enabled, the SBAS will be affected.

5. High dynamic performance will have a little impact on low power mode.

6. The module supports 4800bps~115200bps baud rate and 1Hz-10Hz frequency. It is recommended

that 115200bps baud rate and 1HZ frequency are set before the module enters into low power mode.

7. The modules will automatically come back to the normal mode in difficult environment to keep good

accuracy.

NOTES

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